Adjustable pitch propeller



May 10, 1 932. A, L 1,857,755

ADJUSTABLE PIATCH PRORELLER Filed April 17. 1951 3 Sheets-Sheet 1 I NV EN 1 OR, A/uveo Q. Aka" m 73M 7 m ATTORNEYS.

May 10, 1932. H LL 1,857,755

ADJUSTABLE PITCH PROBELLEK Filed April 17. 1951 r 3 Sheets-Sheet 2 May 10, 1932.

H. A. HALL ADJUSTABLE PI TCH PROPELLER Filed April 17. 1951 3 Sheets-Sheet I5 INVENTOR, 444101 a. Aldp howl 3/ -12 1 ATTORNEYS.

Patented May 10, 1,932

STA'

.HAROLD A. HALL, 01? L GATOS, CALIFORNIA.

ADJUSTABLE rrron rRorELLER Application filed April 17,

in motion, so that when used upon aircraft,

the pilot is able to change the pitch of his propeller during flight, 'in order to secure maximum efficiency under all conditions.

A third object is to provide means for positively and accurately locating and holding the blades in their adjusted position.

These and other objects-and advantages of the invention will become apparent from the following specification which should be read with the understanding that the form, construction and arrangement of the several parts may be varied within the limits of the claims hereto appended, without departing from the spirit of the invention as expressed in said claims.

Reference should be had to the accompanying drawings in which Fig. 1 is a partly broken and partly sectional side elevation of a propeller embodying a preferred form of the invention.

Fig. 2 is a partly broken and partly sectional plan View thereof.

Fig. 3 is a partly broken and partly sectional front elevation thereof.

As a preface to thedetailed description which follows, and in order to permit ready which said blades may be rotated while the propeller is revolving.

The invention also includes two separate but simultaneously actuated locking mecha-' nisms, one of which operates upon the blade adjusting arms to locate and hold them in certain predetermined position. The other locking mechanism is directly associated with the blade sockets, and operates to clamp the blade shanks rigidly therein, so that there can be no possible looseness between the hub and the blades. Both locking mechanisms are operated simultaneously while the propeller .is revolving, through suitably articulated connections leading to an accessible operating member.

In the drawings, the reference numeral 1 Serial No. 530,747. I

designates the shaft of the propeller which, in this instance, may be assumed to be the usual forward extension of an engine crank shaft. 2 is a cylindrical propeller hub splined upon the shaft 1, as indicated at 3 in Fig. 1, and secured thereon by a nut 4 which is screwed upon a threaded end portion 5 of said shaft. The nut 4 has a forward extension 6, which serves to support the apex of a conical shield 7 surrounding the hub of the propeller and inclosing its mechanism to exclude dirt and reduce air resistance. So much is a usual constructionfor mounting a propeller upon the shaft of an aircraft engine.

A stationary plate 8, which may be a portion of the forward end of the engine crankcase, has a tubular forward extension 9 surrounding the propeller hub 2 and provided at its outer end with a bearing 10 for said hub, and a suitable grease retainer 11-. The hub 2 has a flange 12, to which is bolted a plate or disk 13 forming a rear support and closure for the conical shield 7.

The propeller hub 2 has a centralrectangu;

lar portion 2, which carries two opposite radially disposed tubular sockets 14 adapted to receive and hold the shanks 15 of the pro- .peller blades. The outer portions of said.

blades are omitted from the drawings in order to p-ermita scale of suitable size to illustrate the working parts ,of the adjusting and locking mechanism. Each'blade shank adjacent the thrust plate 16, as indicated in Fig. 1, has an integral outwardly extending arm 18, Fig. 2, projecting through a slot 19' in the side of the socket 14. The arm 18 is curved forwardly and then outwardly, as shown in Fig. 2, and has bolted to its outer end an extension 19 which lies between spaced flanges 20 formed upon an adjusting block 21. Theblock 21 is secured by bolts 22 to a yoke 23 which extends across the front of the propeller hub and has its central portion slidably fitted at 24 upon the forwardly extending shank 6 of the shaft nut. Thus when the yoke 23 is moved bodily toward the front or rear, the arm 18 is also moved by the contact therewith of the flanges 20, and the blade shank 15 is thereby turned in its socket 14. The other end of the yoke 23 is connected with a similar arm secured to the opposite blade so that both blades are turned simultaneously. The bolts 22, which secure the block 21 to the yoke 23, pass through slots in said block as indicated, so that the posi* tion of the block upon the yoke may be adjusted by means of a screw 25 and nuts 26. The screw 25 is fixed in a lug 27 projecting from the back of the yoke 23 and passes through a flange 28 formed upon the end of the block 21, (Figs. 1 and 2). This adjustment is for the purpose of equalizing the 1 pitch angles of the two blades.

The yoke 23 is connected by a pair of push rods or bars 29 which extend rearwardly, and are secured to a circumferentially grooved thrust ring 30 surrounding the bearing sleeve 9. Suitable trunnion blocks 31 ride in the groove of the thrust ring 30 and are secured to the lower ends of spaced arms 32 which extend downwardly from a shaft 33 mounted for rocking movement in a stationary frame 34. A lever 35 is secured to and extends upwardly from the rock shaft 33 and has a rearwardly extending operating bar 36 connected with its upper end. See the upper portion of Fig. 1.

The bar 36 extends rearwardly to within reach of the pilot, and is provided with notches 37 adapted to engage a fixed detent 38. By lifting the bar 36 outof engagement with the detent 38 and moving it forward or backward, the thrust ring 30 is moved backward or forward, thereby moving the yoke 23 and turning the blade shanks 15 in their sockets to adjust the pitch of the blades. The bar 36 is provided with a release device 39 comprising an offset rod having a handle 40 at its rear end. By turning the rod through a half revolution in its bearings 41, its offset portion engages the detent 38 and lifts the bar 36 free therefrom, for a purpose to be explained hereafter.

The blade shanks 15 are rigidly clamped Within their sockets 14 by mechanism now to be described. The sockets 14-are split, as shown at 42 in Figs. 1 and 2. The end portion of each socket 14 is surrounded by a slidable collar 43 which is best formed in two halves secured together by boltsextending through ears 44, Figs. 1 and 3. A ring 45, Fig. 1, is screwed into the collar 43, and is provided with an outwardly tapering inner surface. A plurality of segmental wedge blocks 46 lie between the ring 45 and the outer surface of the blade socket 14. Therefore, when the collar 43 and its tapered ring 45 are 1noved outwardly, the blocks 46 are wedges against the socket 14 and contract it tightly about the blade-shank 15. Suitable dowels 47 and a flange 48 on the end of the socket 14 prevent the Wedge blocks 46 from dropping out when released by the inward movement of the collar 43.

Simultaneous opposite movement of the two collars 43 is accomplished by means of opposite systems of connecting links 49 and 50, Fig. 3. There is one such system of links on each side of the propeller hub. Each system consists of three links, the end links 49 having their outer ends pivotally connected at 51 with the collars 43 and their inner ends pivotally connected at 52 with the ends of the central link 50. The latter lies within a carrier member 54 secured to the forward end of a rearwardly extending bar 55, Figs. 1 and 2, whose rear end is integral with a sleeve 56 surrounding the shaft bearing hub 9. The sleeve 56 passes within the thrust collar 30 and carries at its'rear end a second circumferentially grooved thrust ring 57. When said ring 57 is moved forwardly from the position shown in Fig. 1, the center link 50-is also moved forwardly, thereby drawing the collars 43 inwardly toward the center of the propeller by the increasing 'angularity of the links 49. In the position shown in Fig. 1, in which the links 49 and 50 are aligned, the collars 43 are in their outermost positions, in which the sockets 14 are clamped about the blade shanks 15. Forward movement of the thrust ring 57 therefore releases the blade shanks 15, allowing them to be turned in their sockets.

The thrust ring 57 is operated bymechanism similar to that described above for operating the thrust ring 30. This mechanism consists of a pair of trunnion blocks 58 which ride in the groove of the ring 57 and are carried at the lower ends of levers 59. The levers are secured upon a rock shaft 60 mounted in the fixed frame 34 and operated by an upwardly extending lever 61 having a rearwardly extending bar 62 secured to its upper end, (Fig. 1). The bar 62 has a pair of spaced notches 63 adapted to engage a fixed detent 64, one of said notches holding the mechanism in looking position andthe other in free position.

In order to equalize the movement of the two clamping collars 43, the central connecting links 50 are mounted for endwise sliding movement in their carriers 54, thus providing in effect a free floating arrangement of the link systems, so that if one of the clamping collars 43 reaches the limit of itsmovement before the other, the central link 50 will slide a slight distance through its carrier 54 to permit the other collar 43 also to find its seat. Lugs 65, Figs. 1 and 3, are formed upon the blade sockets 14 to serve as stops to limit the inward or retracting movement of the clamping collars 43. Studs 66 are secured in said lugs and extend freely into holes 67 in the clamping collars 43 forming guide pins or dowels to prevent twisting of said collars about the sockets.

A second locking mechanism is provided for the purpose of locating definitely and accurately the adjusted angular positions of the blades. This second locking mechanism is operated simultaneously with the clamping mechanism described above. A plate 68 is secured by screws 69 to the outside of each link carrier 54, forming a cover for said carrier to retain the link 50 therein, as shown best in Fig. 2. The plate 68 extends forwardly and is provided with an inclined slot 70 shown in Figs. 1' and 3. The inner end of a lever 71 is provided with an anti-friction roller 72 whichrides in the slot 70. The lever g 71 is pivoted at 73, and its outer end has slotted engagement at 74 with a slidable looking bolt 75 operating in aligned holes 76 in guide members 77. The latter are connected with the propeller hub at 78 and with its rear cover plate 13 at 79, as shown in Fig 2.

The outer portion of the guide 77 is curved concentrically with the axis of the blade shank 15, and is formed of two parallel bars with a space 77 between them, as shown in Figs. 2 and 3.

The end portion 19 ofthe bent arm 18 which turns the blade in its socket, is extended outwardly and bent forwardly to lie within the space 77 between theguides 77, as shown at 80, and is provided with a plurality of holes 81, Fig. 2, positioned to register with the holes 76 in the guide when the blade is turned to its various desired positions of pitch angle. The locking bolt 75 passes through the aligned holes 76 and 81 in the guide 77 and arm extension 80, thereby locating definitely the angular positions of the blades.

The locking bolt 75 is operated by the movement of the clamp operating mechanism through the instrumentality of the lever 71 and the slot 70 in the plate 68 extending from the link carrier 54, so that when the clamping collars 43 are retracted inwardly to free the blade shanks in their sockets 14, the bolts 7 5 are also withdrawn from engagement with the holes 81 of the arm extensions 80. As shown in Figs. 2 and 3 of the drawings, there are two of the above described locking bolt mechanisms, one on each side of the propeller hub for locking the two respective blades.

The end portions 198O of the blade rotating arms 18 are preferably .removably connected with said armsby bolts 82, Figs. 2 and 3. This enables said end portion to be removed and replaced with others having the holes 81 in different positions when it is de' sired to provide a different series of adjustments for the pitch angle of the blades.

The grooved thrust rings and 57 are supported and guided to prevent wobbling and to cause them to rotate in proper align ment with the propeller by a sleeve 83, Fig. 1, which is secured to the flange 12 of the hub and extends rearwardly around the stationary bearing sleeve 9. The sleeve 56 which carries the rear thrust ring 57 is fitted slidably upon the rotating guide sleeve 83,'and

the forward thrust ring 30 is fitted sl'idably upon the sleeve 56. The guide sleeve 83 and the rear thrust ring sleeve 56 are provided with aligned longitudinal slots 84, and a key or lug 85 is secured to the forward thrust ring 30 and extends into said slots. Thus the two thrust rings, although permitted free longitudinal sliding movement upon the uide sleeve 83, are compelled by the slots 84 and the key 85 to rotate with said guide sleeve. The bars 29 and 55 which extend forwardly from the thrust rings 30 and 57 are thus relieved of twisting strains. The link carriers 54, secured to the forward ends of the bars 55,

are also preferably provided with longitudi nal guides to further insure their stability. These'are shown, in Fig. 3, as T shaped guides 86 secured to the sides of the propeL ler hub and engaged by undercut blocks 87 secured by bolts 88 to the backs of the link carriers 54.

The operation of the device described abovemay be briefly set forth as follows '49 and 50 out of strai'ght line position and retracting the clamping collars 43, to cause the wedge blocks 46 to release the split sockets 14 from their grip upon the blade shanks 15.

. 30 and the yoke 23 to the arms 18 extending from the blade shanks, thereby rotatingthe blades in their sockets to the desired pitch angle. The locking bar 62 is then shifted forwardly again to the position shown in Fig. 1, which shifts the links 49 and 50 back. to their straight line position, thereby causing the clamping collars 43 to again contract the sockets 14 about the shanks of the blades, and also causing the locking bolts 75 to engage the holes 81 in the extensions 80 of the blade adjusting arms 18. The blades are now securely locked in position, and in order to relieve any strain upon the adjusting mechanism and to prevent wear on the thrust ring and its trunnion blocks 31, the bar 36 is raised and held out of engagement with the detent 38 byswinging the offset latch or release bar 39 downwardly.

When the blades are locked they are not only held in proper position definitely and accurately by the engagement of the bolts 75 with the holes 81, but they are also rigidly clamped by the collars 43 and the contracted ends of the sockets 14, so, that there is no possibility of looseness developing between the propeller hub and its blades, even under the severe conditions caused by the continued stresses and vibration of flight.

Obviously, releasing and adjustment of the blades should, not be attempted when the propeller is operating under 'any considerable load. It may be done, however, with ease and safety when the. engine is idling or turning comparatively slowly. When the locking means are released, the blades are held in any particular angular position only by the engagement of the detent 38 with one of the notches.3.7 of the-bar 36, ,but whenthe blades are locked by the locking mechanism the detent 38 has no necessary locking function to perform, and the bar 36 is therefore released from said detent by the release rod 39, in order to prevent strain and wear on the parts and joints of the adjusting. mechanism.

1. An adjustable pitch rop'eller comprising a hub; a blade mounte thereon for movement to adjust its pitch angle; and means operable while the propelleris in motion for tightly gripping said blade to secure it rigidly to said hub. I

2. An adjustable pitch propeller comprismg a hub a blade mounted thereon for movement to adjust its pitch angle; means for clamping said blade rigidly to said hub; separate means for locking said blade in a predetermined angular position; and mechanism operable while the propeller is in motion for actuating said clamping and locking means.

3. An adjustable pitch propeller compris ing a hub; a blade holding socket member carried thereby; a blade mounted in said socket for angular movement to vary its pitch angle; and wedging means operable while the propeller is in motion for clamping said blade rigidly in .said socket.

4. An adjustable pitch propeller comprising a hub; a split socket member carried thereby; a blade having a shank movably mounted in said socket; and means operable while the propeller is in motion for contracting said socket about said shank to lock the blade rigidly to the hub.

5. An adjustable pitch propeller comprising a hub; a split socket member carried thereby; a blade having a shank movably mounted in said socket; a collar movably surrounding said socket; and a wedge between said socket and said collar adapted upon movement of said collar to contract said socket upon said shank.

6. An adjustable pitch propeller comprising a hub; a pair of oppositely disposed split socket members carried thereby; a blade having a shank movably mounted in each socket; a collar movably surrounding each socket; a wedge positioned between each socket and its collar, adapted upon movement of the collar to contract the socket upon the blade shank; and a system of links connecting said collars for simultaneous movement.

7 An adjustable pitch propeller comprising a hub; a pair of oppositely disposed split socket members carried thereby; a blade having a shank movably mounted in each socket; a collar movably surrounding each socket;

a wedge positioned between each socket and its collar, adapted upon movement of the collar to contract the socket upon the blade shank; a system of links connecting said collars for simultaneous movement; and means operable while the propeller is in motion for actuatingsaid links.

8. An adjustable pitch propeller comprising a hub; a pair of oppositely disposed socket members carried thereby; a blade movably mounted in each socket; a clamping member associated with each socket and movable toward and away from the axis of the.

propeller to eifect the clamping and releasing of the blade in its socket; an articulated link connection between the two clamping members adapted by lateral shifting of one of its links to move said clamping members to-- by; a blade'jmovably mounted in said socket;

an arm secured to said'blade; clamping means for rigidly securing sald blade 'WltlllIl said socket; and means adapted for engagement.

with said arm to lock it in a predetermined position. 4

11. .An adjustable pitch propeller comprising a hub; a socket member carried thereby; a blade movably mounted in said socket an arm secured to said blade; clamping means forrigidly securing, said blade within said socket; means adapted for engagement with said arm to lock itin a predetermined posi tion'; and mechanism for operating said clamping means and said locking means simultaneously. p

, 12. An adjustable pitch propeller comprising a hub a pair of blades mounted there in for movement to adjust their pitch angle;

7 an arm extending from eachblade; a yoke straddling the hub andconnected with said arms, one such connection being adjustable 1 to equalize the pitch angles of the two blades;

and means for moving said .yoke to adjust both blades simultaneously. I

13. An adjustable pitch propeller com-' prising a hub; a blade mounted therein for movement to adjustits pitch angle; means for locking said blade in adjusted position; a longitudinally slotted member secured to and coaxial with said hub; a sleeve slidable upon said member, said sleeve having a slot.

registering with the slot in said member; a

said ring; and means'for moving said ring longitudlnally upon said slotted sleeve.

15. An adjustable pitch propeller comprising 'a hub having a forward extension; a pairof blades mounted therein for movement to adjust theirpitch angle; an arm extending from each blade; a longitudinally'movable yoke straddling said hub and having a guide bearing upon said extension, said yoke being connected w th $3.1d arms; and means for motion to adjust said blades.

16. An adjustable pitch propeller comprising ahub; a housing carried thereby, said housing. including a rear plate; a brace extending from said plate forwardly and inwardly to said hub; a blade'mounted in said movingsaidyoke while the propeller is in hub for movement to adjust its pitch angle;

an arm extending from said blade and having a portion lying adjacent to said brace; locking means mounted, upon said brace and adapted'for engagement with said arm to seblade.

)cure the blade in adjusted position; and .means for moving said arm to adjust said In testimony whereof I have signed my name to this specification.

HAROLD A. HALL.

thrust ring secured to said sleeve; a second thrust ring slidably mounted on said sleeve and provided with a key engaging said slots; a connection between said blade and one of said thrust rings whereby adjustment of said blade is caused by longitudinal movement of said ring; a connection between said locking means and the other thrust ring; and means for moving said rings longitudinally while the propeller is revolving. 4

14;. In combination with a stationary hearing sleeve and a rotatable shaft therein, a

propeller comprising a hub secured upon said shaft; a blade movably mounted in said hub; a longitudinally slotted sleeve secured to said hub and rotatably surrounding said bearing sleeve; a thrust ring surrounding said slotted sleeve and adapted for longitudinal movement thereon; a key carried by said ring for engagementwith the slot of said sleeve; 9. connection between said blade and 

